Under the existing art, the manufacture of a double-enveloped electric lamp typically involves the following steps. A light-source capsule having two lead-in wires is mounted on a glass stem support. The capsule and stem are inserted into the outer envelope. The glass stem support is flame sealed to the glass outer envelope. The outer envelope is evacuated, a desired fill gas may be introduced into the outer envelope, and the outer envelope is hermetically sealed. A lamp base is mounted on and cemented to the neck of the outer envelope. One of the capsule lead-in wires is soldered to the insulated tip of the base. The second lead-in wire is soldered or welded to the outer shell of the base.
The described manufacturing process is relatively costly. The fabrication of a hermetic seal between the lead-in wires and glass stem and between the stem and outer envelope requires considerable technological skill and quality control.
A double-enveloped electric lamp, of equivalent or improved quality compared with those currently available, which can be manufactured by a process simpler and less expensive than the process hereinbefore described would constitute an advancement in the art.